Automatic assembly machines are widely used in the assembly of components onto printed wiring boards. The printed wiring board is positioned and the placement program of the assembly machine directs the machine to pick up components and place them in the correct orientation and position on the printed wiring board. Many printed wiring boards have quite a number of components assembled thereon, and thus it is desirable to test the components before they are permanently secured in place. The later the test occurs in the assembly sequence, the higher the reliability because there is a lower chance of part damage or part mixup after the test. Thus, it is conventional for the pick-and-place machine to pick up a component which is thought to be a correct and operative component. This component is taken to a test position where it is tested to determine that the component is correct and operative. Thereupon, it is picked up and positioned at its attachment position on the printed wiring board. After such positioning on the printed wiring board, it is permanently secured, as by reflow soldering. The pickup of the component and the movement of the component to the test position, followed by the discrete step of testing the component, again picking up the component and moving it to its attachment position, and placing it thereon is a multi-step process which can be simplified. Simplification can be achieved by testing the component while it is in transit between the pickup position and the attachment position This eliminates the placement of the component at the test station and the subsequent pickup of the component at that station. Machine time is reduced by eliminating the intermediate step of placement in the test position and the consequent possible mixup of parts at the test position, it is desirable to test the component while it is in route between the pickup position and the placement position, thereby also eliminating a discrete station.